A battery pack usually includes multiple cells connected in series to supply electric power to electronic equipment, such as an electronic vehicle, a portable computer, an electronic camera, or the like. The battery pack is usually equipped with multiple control circuits that monitor the state of each cell for capacity calculations and battery cell protection.
FIG. 1 illustrates a conventional battery management system 100 for a battery pack 102. In the battery pack 102, cells 104, 106, and 108 are connected in series. The battery management system 100 can include control circuits 114, 116, and 118 for respectively managing the cells 104, 106, and 108. The control circuits 114 and 116 are coupled to the cells 104 and 106 through a first path 125. The control circuits 116 and 118 are coupled to the cells 106 and 108 through a second path 127. If the different control circuits consume different amounts of currents, there will be an undesired current flowing through the first path 125 and the second path 127, which may cause an imbalance between the cells and may shorten battery life.